This invention relates to muffling noise emitted from the vacuum columns in a magnetic tape transport. More particularly, the invention relates to containing the noise generated by the movement of magnetic tape in a vacuum column within the vacuum column and dissipating that noise within the vacuum column.
As the speed of movement and acceleration of magnetic tape in a magnetic tape transport increases, sound waves created by the tape become a noise problem during operation of the tape transport. In fact, the highly compliant conditions formed by the tape loop in a vacuum column take the tape loop a credible low-frequency speaker. Of course, during data processing operation, low-frequency sound waves created by the stop/go motion of the tape are undesirable.
In the past, this noise produced by the tape loop in the vacuum column has been essentially sealed off from the outside by the use of a door on the front of the tape transport. This solution to noise generated by the tape loop, however, is no longer adequate as tape speeds increase, interblock gaps decrease, and access time to data in a block decrease. While noise muffling can be advantageous at lower speeds and lower acceleration, certainly where speeds are running over 200 ips and acceleration of tape is running better than 3 .times. 10.sup.5 in./sec..sup.2, noise muffling begins to become attractive to keep the operation of the tape transport at a relatively quiet level.
Helmholtz resonant cavities to muffle noise have been applied to many devices such as automobile engines and jet aircraft engines. These applications, however, are not particularly useful in muffling noise in a magnetic tape transport. The problems that require solution when muffling vacuum columns in a tape transport include the selection of noise baffles and the placement of noise baffles so as to achieve maximum muffling without adversely effecting the loading and running of tape in the vacuum columns.